Device for helically deforming a band to form a tube

ABSTRACT

A device for helically deforming a sheet metal band into the form of a tube comprising an inner bending roll and two outer bending rolls, the axes of all of which during the deformation procedure of the sheet metal band may be displaced axially and parallel to each other. In addition, the inner bending roll is vertically adjustable and the two outer bending rolls are each individually vertically and laterally adjustable, and the curvature of the tube while being formed is measured by a scanning device which upon deviations of the tube curvature from a predetermined dimension produces electric impulses which effect an adjustment of the vertical position of the inner bending roll.

United States Patent [1 1 Krakow DEVICE FOR HELICALLY DEFORMING A BAND TO FORM A TUBE [75] Inventor: Heinz Krakow, Hamburg, Germany [73] Assignee: Blohm & Voss AG, Hamburg,

Germany 22 Filed: Oct. 26, 1971 21 Appl. No.: 192,135

[30] Foreign Application Priority Data Oct. 30, 1970 Germany P 20 53 266.5

[52] US. Cl 72/12, 29/4773, 72/173 [51] Int. Cl. B211) 37/00, 821d 5/14 [58] Field of Search 72/49, 142, 173,

[56] References Cited UNITED STATES PATENTS 3,650,015 3/1972 Davis 29/4773 I 51 Dec. 4, 1973 Primary Examiner-Charles W. Lanham Assistant Examiner-Robert M. Rogers Attorney-Benjamin H. Sherman et al.

57 ABSTRACT A device for helically deforming a sheet metal band into the form of a tube comprising an inner bending.

roll and two outer bending rolls, the axes of all of which during the deformation procedure ,of the sheet metal band may be displaced axially and parallel to each other. In addition, the inner bending roll is vertically adjustable and the two outer bending rolls are each individually vertically and laterally adjustable, and the curvature of the tube while being formed is measured by a scanning device which upon deviations of the tube curvature from a predetermined dimension produces electric impulses which effect an adjustment of the vertical position of the inner bending roll.

22 Claims, 7 Drawing Figures 1 DEVICE FOR HELICALLY DEFORMING A. BAND TO FORM A TUBE The invention relates to a device forhelically .deforming a sheet metal bandto form a tube by means of inner and outer bending rolls.

When producingsheets andtbands, as they are employed, for instance, in the production ofhelical seam:

tubes, it is of known importance thatcertain produc-. tion tolerances have to be maintained. These produc-, tion tolerances relate to themaintenance of dimensions of angularity of thematerialjto be worked upon. Also required are tensile values and elongation values'which are tested by means of random samples and haveto be. within predetermined,tolerances. It has been discovered, however, thateven .such sheetmetal. bands which in each caseliewithinthe permissible-tolerances, that the bending rolls, so that non-circular tube shapesand other difficulties occurduring the welding ofthe helical seam.

Thesedisadvantagesare themoreseriousand consequential, the thicker the band, namely the greater the.

differences in the forces which oppose :the deformation of the band and the larger the. diameter of the-tube, then the smaller is the:curvature to becproduced.

The object of the inventionis a device for producing helically formed tubesand which compensatesfor. all i of theabove-mentioned differences in the material.

in accordance with the invention, the axesof all bending rolls during the deformation of the band are arranged at least in onedirection parallel slidable in the device. This means thatthe axes of the inner and of the outer bending rollsare controlled partly automatically or partly programmatically or manually, axially, horizontally and vertically independently of each other during their deformingoperationand maysubsequently be displaced parallel to one anothers This arrangement makes itpossible that for each quality of sheet metal and for each thickness of the sheet metal the correct position of the axes of the. bend ing rolls to each other is determined inrelationto sheet metal values ascertainedfroma previous bendingtest. during the adjustment to a predetermined tube 'diameter and for different tube diameters.

Such an adjustment is preferablyaccomplished at rel-. atively low expense with a device in which duringthe deformating operation the. axes of the inner bending. rolls are vertically adjustableand also laterally displaceable.

Such a construction has the advantage that for the. compensation-of the differencesnin the. sheet metal thickness and of theuquality of the sheet metal, the bending rolls, are adjusted only in the mentioned mannor in order to take into consideration at once and continuously without interruption of thedeformation operation.

Even though one determines the values of. the sheet metalprior to the entranceof the sheet metal band into the deformation machine and characterizes thesame, for instance, by color markings,andby a manually vertical adjustment of the inner, bendingrolls, an. automatic operation of theentire procedure is still to be. preferred.

This automatic procedure in accordance-with the invention is attainedin that the tube curvature at the outlet of the bending rollers is measured by a scanning device, whereby the deviations from the desired curvature of the tube diameterin the form of impulses are usedfor the operation of the vertical adjustingdevice of the inner bending roller.

The bending rolls donot have a cylindrical form but in accordance with the. invention are constructed as bend-resistant supports which carry individual discshaped. deforming rolls.

It is advisable to arrange the disc-shaped deforming rolls'of .theinner bending roll on a roll'supportwhich. is supportedatleast. at two points along the direction.

ofthe axis ofthe tube vertically slidablewith respect to pedestal-like frames; In such an. arrangement, the

frames maybe in direct force-transmitting connection with the supports for the exterior bendingrolls in order to receive the deformation forces inaa closed frame structure.

The vertically adjustable-supports of the roll carrier may also beflexible and constructed in the form of a sliding key .mechanismwhose slidable key is actuated v by a motor which is controlled by the tube curvature scanning device.

Such a vertical adjusting device operates continuously and fully automatically and has a good efficiency. This device is not very expensive and any too highfrictional forces may be taken up by anti-friction bearings.

Afurther advantageous construction of the device of in thedir'ection of the axis of the tube. This means the arrangement may accommodate a material having a smaller Widthwith-a shorter stressed length of the inner bending roll. This arrangement also makes it possible to move the roll carrier with the highly stressed rolls outwardly from the tube, for instance, for the purpose of exchanging without difficulty any damaged or jammed rolls.

Owing to the deformation pressures taken up by the inner roll,1the roll carrier will be subject to a very small bending or flexure. The shape of this flexurexchanges with the position of the inner bending roll and of the roll support in axial direction, namely, with the position of theaxially non-slidable supports of the roll support and the bearing box, respectively, with respect to the frame. lnorder to obtain with reference to thewidth of the band a symmetrically extending bending line, namely, a symmetrical bending stress of the band over its width, it is necessary to balance out" the roll support.

This is accomplished in that the outer vertically adjustablesupports of the roll support or therbearingbox,

respectively, are for instance madevertically adjustable with the assistance of a motor-driven eccentricshaft independently of the scanning device which measures the tube curvature. The motor drive of the eccentric.

shaft may be controlled by a water balance or another suitable inclination measuring device.

Finally the roll support may have at its inner end facing the tube an inner tube support which is provided with rollers on arms, whereby all of the rollers at the same time are adjustable in radial direction and subject the inner wall of the tube to pressure.

Furthermore, during the deformation operation, the tube diameter-if desired-in cooperation with a small change of the inlet angle, may be increased or decreased within narrow limits. The possibility of making the entire calibration of the inner surface of the tube centric is important for the reason, that only the roll support with the assistance of the above-mentioned gear drive or any other means may be removed fro the tube.

While the devices used for the adjustment of the inner bending roll during the operation of the deformation machine operate substantially automatically, the outer bending rolls, as soon as the inner bending roll reaches the limit range of its operativeness by means of suitable drives, which also operate during the operation of the deformation either manually or programmatically, i.e. in relation to the effectiveness of the vertical adjustment of the inner bending roll, are adjusted. The invention makes use of the knowledge that the influencing of the radius of curvature of the tube by solely adjusting the vertical position of the inner bending roll only in the range of certain positions of the outer bending rolls yields a maximum result.

The devices for the adjustment of the outer bending rolls are actuated by electrical, hydraulical or electrohydraulical drive means. In this manner, the axes of the outer bending rolls may be adjusted in the axial, horizontal and in the vertical direction in such a manner that at the average thickness of the sheet metal and the average quality of the sheet metal under due consideration of the size of the still available operating range of the automatic adjusting means, the inner bending roll produces the desired curvature of the tube diameter. If then the average values of the thickness of the sheet metal and quality or thickness of the sheet metal are not obtained during the deformation operation, i.e. when at certain parts the desired tube curvature cannot be obtained, then there will come into operation first of all the tube curvature scanning device which controls the vertical adjusting device of the inner bending roll, so that the previously adjusted tube curve is increased or decreased.

In addition to the horizontal, vertical and axial adjustability of the axes of the outer bending rolls, the invention provides that the bearings of the outer bending rolls, which take up pressure may be pivoted by drive means about axes which extend parallel to the axes of the rolls. In this manner, these bearings are not eccentrically stressed when the tube diameters are different, so that the lubrication of the bearing and the attachment of the bearing are not in danger, because the pivotal adjustment which is possible has the result that the center line of the bearings and the direction of the force on the bearings are substantially in coincidence.

Finally, the invention also provides a device for the adjustment of the attack angle of the deformation rolls in correspondence with the inlet angle of the sheet metal band into the deformation machine.

All of these described adjusting devices for the outer bending rolls are provided in an embodiment for each An embodiment of the device of the invention is diagrammatically illustrated in the accompanying drawings in which:

FIG. 1 illustrates the arrangement of the inner bending roll in side elevation.

FIG. 2 illustrates an end view of the inner tube support.

FIG. 2a illustrates in a partial section a inner tube support.

FIG. 3 illustrates in a side elevation view the arrangement of the outer bending rolls. a

FIG. 3a is a top view of the arrangement shown in FIG. 3.

FIG. 4 illustrates an end view of the device from the left-hand side of the FIGS. 3 or 30.

FIG. 5 is a diagrammatic illustration of the automatic control of the attack angle of the deformation rolls as determined by the desired dimensions of the tube to be produced.

Referring to the drawings, the device 1 which deforms a sheet metal band 2 into a helical seam tube 3 having the longitudinal axis 4 comprises basically a plurality of frames 5 which together with a foundation 6 constitute a closed structure for resisting the bending forces which occur during the deformation of the band 2.

An inner bending roll 10 comprises a series of individual deforming rolls 11 which are mounted one next to each other on a common roll support or shaft 12 which is axially movable within a bearing box 13, whereby the axial movement is accomplished by a toothed rack 21 which is actuated to be axially movable by a drive 22,

The bearing box 13 is supported by means of vertically adjustable supports 14 and 14' within the frame 5. Each of the vertically adjustable supports 14 and 14 consist of a sliding key mechanism 15, both of which are operated by a common drive 16 which in turn is controlled by a tube curvature scanning device 17. (FIG. 5).

The roll support 12 and the bearing box 13, respectively, are pivotally supported in the two vertically adjustable supports 14 and 14', namely in such a manner that a tilting movement of a roll support 12 from the horizontal is possible. Viewed from above (FIG. 3a) the pivot axis extends at right angles to the longitudinal axis of the tube to be produced. This arrangement is not very apparent from the drawing because one has to deal with shoulder bearings which permit minor pendulum movements.

The roll support 12 and the bearing box 13, respectively, are guided in the parts of the frame 5 of the device by parallelogram guides which, for instance, may have the form of articulated lever systems, so that a twisting of the roll supports during vertical movements is not possible.

Between the outer vertically adjustable support 14 and the bearing box 13 is arranged an ecentric shaft 18 whose position effect is one-sided vertical adjustment of the bearing box 13 and therewith an adjustment of the roll support 12, which however is independent of the tube curvature scanning device 17. The eccentric shaft 18 is rotated by a motor 19 by means of a gearing detail of the and this motor 19 may be controlled by an inclination measuring device 20 (FIG. 5).

With the assistance of a toothed rack 21 provided on the roll support 12 and a drive 22 on the bearing box 13, the roll support 12 may be moved relatively to the bearing box 13 in the direction of the horizontal axis 4 of the tube.

At the inner end of the roll support 12 is arranged an I inner tube support 23 (FIGS. 1 and 2) which is provided with radially extending arms 24 atthe outer end of which are mounted rollers 25 which by means of a central drive 26 and a gear 27 (FIG. 2a) and shafts28 and an elastic intermediate member 29 are pressed against the inner wall of the tube 3.

For the vertical and axial adjustment of the outer bending rolls 30 and 31 and their deformation rollers 32 and for each of the two outer bending rolls 32, are

provided two adjusting devices with relatively to each other slidable adjusting wedges 33 and 35. The latter are associated with drive means 34 and 36and furthermore for the horizontal adjustment each one of the outer bending rolls is provided with a lateraladjustment device having adjusting wedges 37 and 37' operdone, the vertical adjustment is changed. The .slidable wedges 37 and 37' are arranged in the wedge member 33.

For the swinging movement of the bearings each one of the same is provided with a separate drive 39 and 39', respectively. These bearings swing the bending rolls 30,31 in relation to the center point of the tube in which or nearby thereto the symmetry lines of the bearings of the two outer bending rolls 30 and '31 should intersect.-

The axis for the swinging movement of the bearings toward the center point of the tube may be selected as desired. Preferably, this axis is arranged in the plane in which the bending roll engages the tube. The bearings for the lower bending rolls are therefore swung more when a tube of a smaller diameter is being made and is swung to a smaller degree when a tube of a larger diameter is being made.

The three bending rolls 10, 30 and 31 are each provided with a series of deformation rolls 11 and 32, re spectively, which are disc-shaped and by themselves, with respect to the axis of the respective bending roll, are adjustable about a vertical axis in such a manner that the planes of the disc-shaped deformation rolls 11 and 32 with respect to the axis of the associated roll may assume an attack angle deviating from 90. A change of the attack angle of the deformation rolls is necessary when a change of the inlet angle of the sheet metal band into the deformation device takes place. The change in the attack angle is effected in this case for the outer bending rolls 30 and 31 by the drives 40 and 40' and for the inner bending roll with the assistance of a similar drive not illustrated.

In accordance with the invention, the change of the attack angle of the deformation rolls 11 and 32, respectively, of the three bending rolls is also employed for the purpose of accomplishing a continuous control of the tube by making corrections resulting from the tube bending operation so as to protect the deformation rolls against excessive lateral forces which could lead to a destruction of these rolls, when on one hand the inlet angle of the band changes constantly within certain limits, and when on the other hand the attack angle of the deformation rolls is not in agreement therewith.

For this purpose the control system illustrated in FIG.

5 is employed This control system comprises the al-' ready mentioned tube curvature: scanning device 17 and in addition thereto four measuringinstruments 50 which are circularly arranged so as to be each apart from each other and which continuously measure the oval shape and the diameter of the finished welded tube. The measured values are transferred as actual values to the actual value potentiometers 51 and 52, of

whichthe potentiometer 51 measuresthe ovalshape and the potentiometer 52 measures diameter values, whilethe tube curvature actual values measured by the scanning device 17 are indicated at 53.

These actual value potentiometers are arranged for the sake of comparison opposite of the desired value potentiometers 54, 55 and 56. The differences between the said desired values and the measured actual values are amplified in their electrical values which are converted in order to operate by means of control devices 62, 63, and 64 associated drive means (such as 40 and 40') which adjust the deformation rolls of the three bending rolls. For the amplification and conversion of the differential values determined from the desired values and the actual values potentiometer are provided the devices57, 57 and 57". 59 indicates an indicating instrument for the attack angle of the three deformation roll units. This indicating instrument may be selectively switched at 58 to either one of the roll units. The

indicating instrument 60 indicates the vertical position of the inner deformation roll unit. The adjustment in vertical direction is accomplished by the adjusting drive 16 and indicated by the potentiometer connected thereto. The operating member for the vertical adjustment drive may consist, as indicated in the drawing, of a push-button P or another automatically actuating adjustment member. The indicating instrument 61 indicates the inclination of the roll support 12 of the inner bending roll 10 on which are arranged the individual disc-shaped deformation rolls 11. An inclination measuring instrument 20 effects an automatic operation of the drive 19 of the eccentric shaft 18, both of which are arranged on the outer end of the roll support 12.

i in FIG. 5 indicates alternating current motors, indicates a three-phase alternating current motor, W indicates switching means for the automatic adjustment of the adjusting means in relation to the desired value potentiometers 54, 55 and 56. U indicates a manually operable changeover switch at 58, and Poti indicates potentiometers. i V

It has been discovered that the change of the attack angle of the deformation rolls, particularly in deformation devices for tubes having a large diameter and a very thick wall has a deciding alleviation effect during a change of the inlet angle of the sheet metal band and that in such a case a swingable arrangement of the deformation station with respect to the sheet metal band is not necessary.

However, the deformation procedure is also then considerably alleviated, for instance, by the arrangement of the adjustable deformation rolls because the inlet direction of the band always is in the direction of the plane of the direction of the deformation rolls.

The invention permits the practice of a production method for making helical seam tubes which is based on a careful testing of the material to be deformed as a starting product and/or of the dimensions of the tube as end product, and comprises a suitable device and also a control of this device which permits the continuous automatic production of tubes having a large diameter and a thick wall.

What I claim is:

1. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, and means for so supporting said shaftmeans during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, and mounting means for said rolls so that said rolls are slidable parallel in at least one direction and are also vertically adjustable during the forming operation responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing.

2. Device according to claim 1, including means for vertically adjusting the shaft means of said inner bending rolls during said deforming operation and means for vertically and laterally adjusting the shaft means of said outer bending rolls during said deforming operation.

3. Device according to claim 1, in which said inner bending roll comprises a plurality of serially arranged deformation rollers mounted on a common shaft 12), the latter being rotatably supported for vertical adjustment at least on two places within the frame of the device.

4. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said 8 thereon into engagement with the inner wall of the tube.

7. Device according to claim 1, including bearings for said outer bending rolls, and drive means (39) for pivotally adjusting said bearings about axes extending parallel to axes of said rolls.

8. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers (11, 32) which are mounted on shafts rotatable about parallel axes.

9. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers (11, 32) which are mounted on shafts rotatable about parallel axes, and including means for adjusting the attack angle of the disc-shaped deformation rollers about vertical axes.

10. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers(11, 32) which are mounted on shafts rotatable about parallel axes, and including means for adjusting the attack angle of the disc-shaped deformation rollers about vertical axes, the attack angle of said disc-shaped deformation roller being adjusted during the deformation operation in correspondence with the deviations of the tube curvature from the desired dimensions of the tube being formed.

1 1. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, scanning means for measuring the curvature of the tube at the outlet end of said bending rolls, means for vertically adjusting the shafts for said inner bending rolls, means for operating said vertically adjusting means, and means for producing electric signals from the measurement deviations between the measurements made by said scanning means and the desired dimension of the tube diameter, and means for causing said signals to operate'said operating means for said vertically adsheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, said inner bending roll comprises a plurality of serially ar-' ranged deformation rollers mounted on a common shaft, the latter being rotatably supported for vertical adjustment at least on two places within the frame of the device, means comprising slidable wedge gearing for flexibly supporting said common shaft, an electric motor for operating said wedge gearing, and a scanning means for measuring the curvature of said tube, said scanning means controlling the operation of said electric motor.

5. Device according to claim 4, including a bearing box for said common shaft mounted displaceable in direction of said tube in the frame of the device.

6. Device according to claim 4, including a tube support (23) for the inner end of said common shaft (12), said tube support comprising substantially radially disposed arms provided each with a roller at their outer ends which'engage the inner wall of the tube, and means for radially urging all of said arms and rollers justing means.

12. Device according to claim 11, including measuring instruments (50) in addition to said scanning means for determining the diameter of the ovality of the tube.

13. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be .formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, vertically adjustable means for supporting the outer bending rollers, and a motor-operated eccentric drive shaft connected with said supporting means for operating said vertically adjustable means.

14. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said .shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, said a inner and outer rolls including two outer bending rolls mounted on separate shafts arranged in horizontal spaced relationship, and driven slidable wedge gearings for adjusting the distance between said shafts.

15. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, the aforesaid rolls including two outer bending rolls (30, 31) mounted on separate shafts arranged in horizontal spaced relationship, and driven slidable wedge gearings (37) for adjusting the distance between said shafts, and additional driven slidable wedge gearings (33, 35) for adjusting the shafts of said bending rolls (30, 31) in axial and vertical directions.

16. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet'metal band that said shaft means at least in one direction are slidably displaceable along their axes, and including, in combination, scanning means and measuring instruments for determining the actual dimensions of the tube in relation to adjusted desired dimensions of the same, said combination forming an automatic control means for drive means which adjust the attack angles of the deformation rollers constituting parts of said bending rolls.

17. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, and means forso supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, and mounting means for said rolls so that said rolls are slidable parallel in at least one direction during the forming operation responsive to variations in the coefficient of elasticity in the sheet 'metal band for enabling the rolls to adjust to the desired diameter of the tubing.

18. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band.

19. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction and also vertically responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band.

20. A method of helically deforming a sheet metal band comprising the steps of welding together a series of sheet metal pieces to form a sheet metal band, relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band. i

21. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, while relatively moving the sheet metal band causing the rolls to slide parallel in at least one'direction responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band, measuringthe thickness of the band during the helical deformation thereof and causing relative movement of the rolls where the meaincluding a scanning device for ascertaining deviations of the tube curvature from a predetermined dimension and means responsive to said scanning means for vertically moving the centermost bending roll in response to the sensed deviations. 

1. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, and means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, and mounting means for said rolls so that said rolls are slidable parallel in at least one direction and are also vertically adjustable during the forming operation responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing.
 2. Device according to claim 1, including means for vertically adjusting the shaft means of said inner bending rolls during said deforming operation and means for vertically and laterally adjusting the shaft means of said outer bending rolls during said deforming operation.
 3. Device according to claim 1, in which said inner bending roll comprises a plurality of serially arranged deformation rollers mounted on a common shaft (12), the latter being rotatably supported for vertical adjustment at least on two places within the frame of the device.
 4. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, said inner bending roll comprises a plurality of serially arranged deformation rollers mounted on a common shaft, the latter being rotatably supported for vertical adjustment at least on two places within the frame of the device, means comprising slIdable wedge gearing for flexibly supporting said common shaft, an electric motor for operating said wedge gearing, and a scanning means for measuring the curvature of said tube, said scanning means controlling the operation of said electric motor.
 5. Device according to claim 4, including a bearing box for said common shaft mounted displaceable in direction of said tube in the frame of the device.
 6. Device according to claim 4, including a tube support (23) for the inner end of said common shaft (12), said tube support comprising substantially radially disposed arms provided each with a roller at their outer ends which engage the inner wall of the tube, and means for radially urging all of said arms and rollers thereon into engagement with the inner wall of the tube.
 7. Device according to claim 1, including bearings for said outer bending rolls, and drive means (39) for pivotally adjusting said bearings about axes extending parallel to axes of said rolls.
 8. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers (11, 32) which are mounted on shafts rotatable about parallel axes.
 9. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers (11, 32) which are mounted on shafts rotatable about parallel axes, and including means for adjusting the attack angle of the disc-shaped deformation rollers about vertical axes.
 10. Device according to claim 1, in which said bending rolls comprise each a plurality of disc-shaped deformation rollers (11, 32) which are mounted on shafts rotatable about parallel axes, and including means for adjusting the attack angle of the disc-shaped deformation rollers about vertical axes, the attack angle of said disc-shaped deformation roller being adjusted during the deformation operation in correspondence with the deviations of the tube curvature from the desired dimensions of the tube being formed.
 11. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, scanning means for measuring the curvature of the tube at the outlet end of said bending rolls, means for vertically adjusting the shafts for said inner bending rolls, means for operating said vertically adjusting means, and means for producing electric signals from the measurement deviations between the measurements made by said scanning means and the desired dimension of the tube diameter, and means for causing said signals to operate said operating means for said vertically adjusting means.
 12. Device according to claim 11, including measuring instruments (50) in addition to said scanning means for determining the diameter of the ovality of the tube.
 13. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, vertically adjustable means for supporting the outer bending rollers, and a motor-operated eccentric drive shaft connected with said supporting means for operating said vertically adjustable means.
 14. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheEt metal band that said shaft means at least in one direction are slidably displaceable along their axes, said inner and outer rolls including two outer bending rolls mounted on separate shafts arranged in horizontal spaced relationship, and driven slidable wedge gearings for adjusting the distance between said shafts.
 15. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, the aforesaid rolls including two outer bending rolls (30, 31) mounted on separate shafts arranged in horizontal spaced relationship, and driven slidable wedge gearings (37) for adjusting the distance between said shafts, and additional driven slidable wedge gearings (33, 35) for adjusting the shafts of said bending rolls (30, 31) in axial and vertical directions.
 16. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, and including, in combination, scanning means and measuring instruments for determining the actual dimensions of the tube in relation to adjusted desired dimensions of the same, said combination forming an automatic control means for drive means which adjust the attack angles of the deformation rollers constituting parts of said bending rolls.
 17. Device for helically deforming a sheet metal band to form a tube therefrom, comprising inner and outer bending rolls for engaging the inner wall and the outer wall of the tube to be formed, shaft means on which said rolls are mounted, and means for so supporting said shaft means during the deforming operation on said sheet metal band that said shaft means at least in one direction are slidably displaceable along their axes, and mounting means for said rolls so that said rolls are slidable parallel in at least one direction during the forming operation responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing.
 18. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band.
 19. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction and also vertically responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band.
 20. A method of helically deforming a sheet metal band comprising the steps of welding together a series of sheet metal pieces to form a sheet metal band, relatively moving the band with respect to a series of inner and outer bending rolls, and while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction rEsponsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band.
 21. A method of helically deforming a sheet metal band comprising the steps of relatively moving the band with respect to a series of inner and outer bending rolls, while relatively moving the sheet metal band causing the rolls to slide parallel in at least one direction responsive to variations in the coefficient of elasticity in the sheet metal band for enabling the rolls to adjust to the desired diameter of the tubing and thereby controlling the radius of curvature of the thus helically deformed sheet metal band, measuring the thickness of the band during the helical deformation thereof and causing relative movement of the rolls where the measurements indicate that a vertical adjustment of the rolls is required, and vertically causing relative movement of the rolls in response to the aforesaid measurement step where required.
 22. The device of claim 17 further characterized as including a scanning device for ascertaining deviations of the tube curvature from a predetermined dimension and means responsive to said scanning means for vertically moving the centermost bending roll in response to the sensed deviations. 